A method and apparatus of encrypting optical images using binarization or phase only information is presented with a number of ways to secure the image also being provided. An image to be encrypted is first multiplied by a random phase function. The Fourier transform of the product of the image and the random phase function is then multiplied by another random phase function in the Fourier (or Fresnel) domain. Taking the inverse Fourier (or Fresnel) transform, an encrypted image in the output plane is obtained. Alternatively, the image to be encrypted can be phase encoded and then encrypted to provide an extra level or security. The image can be secured using one key in the Fourier or Fresnel domain followed by phase extraction. This encrypted image may then binarized, which may include binarizing the phase-only part of the encrypted image. The use of binarization enables ease of implementation and data compression while still providing recovery of images having good quality. The original image may be recovered from the phase-only part of the encrypted image, the binarized encrypted image, or the binarized phase-only part of the encrypted image.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method of encryption and decryption comprising the steps of: encrypting original information to generate encrypted information; binarizing at least a part of said encrypted information to generate binarized encrypted information, said binarizing at least said part of said encrypted information comprises binarizing at least one of a real part and an imaginary part of said encrypted information, said binarized encrypted information is expressed as φ R _ ( x ) = { 1 if Re [ φ ( x ) ] > Median { Re [ φ ( x ) ] } - 1 if Re [ φ ( x ) ] < Median { Re [ φ ( x ) ] } for said real part, and φ 1 _ ( x ) = { 1 if Im [ φ ( x ) ] > Median { Im [ φ ( x ) ] } - 1 if Im [ φ ( x ) ] < Median { Im [ φ ( x ) ] } . for said imaginary part; and decrypting said binarized encrypted information to provided decrypted information indicative of said original information.
2. The method of claim 1 , wherein the original information comprises optical images.
3. A method of encryption and decryption comprising the steps of: encrypting original information to generate encrypted information; binarizing at least a part of said encrypted information to generate binarized encrypted information, said binarizing at least said part of said encrypted information comprises binarizing a phase part of said encrypted information, said binarized encrypted information expressed as φ ψ _ ( x ) = { 1 if Re [ φ ( x ) ] ≥ 0 - 1 if Re [ φ ( x ) ] < 0 for said phase part; and decrypting said binarized encrypted information to provided decrypted information indicative of said original information.
4. The method of claim 3 , wherein the original information comprises optical images.
5. A method of encryption and decryption comprising the steps of: encrypting original information to generate encrypted information; binarizing at least a part of said encrypted information to generate binarized encrypted information, said binarizing at least said part of said encrypted information comprises binarizing at least one of a real part and an imaginary part of said encrypted information, said binarized encrypted information is expressed as φ R _ ( x , y ) = { 1 if Re [ φ ( x , y ) ] > Median { Re [ φ ( x , y ) ] } - 1 if Re [ φ ( x , y ) ] < Median { Re [ φ ( x , y ) ] } for said real part, and φ 1 _ ( x , y ) = { 1 if Im [ φ ( x , y ) ] > Median { Im [ φ ( x , y ) ] } - 1 if Im [ φ ( x , y ) ] < Median { Im [ φ ( x , y ) ] } . for said imaginary part, and decrypting said binarized encrypted information to provided decrypted information indicative of said original information.
6. The method of claim 5 , wherein the original information comprises optical images.
7. A method of encryption and decryption comprising the steps of: encrypting original information to generate encrypted information; binarizing at least a part of said encrypted information to generate binarized encrypted information, said binarizing at least said part of said encrypted information comprises binarizing a phase part of said encrypted information, said binarized encrypted information expressed as φ ψ _ ( x , y ) = { 1 if Re [ φ ( x , y ) ] ≥ 0 - 1 if Re [ φ ( x , y ) ] < 0 for said phase part; and decrypting said binarized encrypted information to provided decrypted information indicative of said original information.
8. The method of claim 7 , wherein the original information comprises optical images.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
December 13, 2002
May 1, 2007
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